The Crank Position Sensor (CKP) on a 1991 Ford Explorer is located on the
passenger side of the engine, usually
near the bottom of the engine block, close to the crankshaft pulley. It's often mounted on a bracket or directly to the engine block itself. You'll likely need to get under the vehicle to see it clearly.
Because there's some variation depending on specific engine type (4.0L V6 is most common but there might be others), a visual inspection using a repair manual or a diagram specific to your Explorer's engine is highly recommended. Pictures online for a '91 Explorer CKP sensor location would also be beneficial.
